Machine for developing photographic prints



June 27, 1933. B. F. HALL 1,916,108

MACHINE FOR DEVELOPING PHOTOGRAPHIC PRINTS Filed March 4, 1931 5 Sheets-Sheet 1 June 27, 1933. B. F. HALL MACHINE FOR DEVELOPING PHOTOGRAPHIG PRINTS Filed March 31 3 Sheets-$heet 2 INVENTORS EE/V/A/Y/A/ 7 F7 #4124 June 27, 1933.

B. F. HALL MACHINE FOR DEVELOPING PHOTOGRAPHIC PRINTS Filed March 4, 1931 3 Sheets-Sheet 3 Patented June 27, 1933 PATENT OFFICE BENJAMIN FAIR-FAX HALL, OF LONDON, EIJGLAND MACHINE FOR DEVELOPING PHOTOGRAPHIC PRINTS Application filed March 4, 1931, Serial No. 520,054, and in Great Britain April '7, 1930.

This invention has reference to photographic print developing machines used for developing paper, on which images have been printed, by wetting or wiping or damping the surface with the developer, and has for its object to construct a machine into which the paper is so fed that its sensitized surface is carried over and maintained in contact with an arc of the developer roller by cap- 1 illary attraction without either manual or mechanical assistance before passing between the squeegee or pressure roller and said developer roller, whereby I am enabled to obtain a clearer and more distinct reproduction of the print without discolouring or practically without discolouring the paper on which the reproduction is printed when a suitable developer is employed.

According to this invention the machine 5 consists of two rollers made of or coated with rubber or other suitable material, the lower one, which revolves in a bath containing the developing solution, being gear driven, and the upper one, which is preferably though not necessarily mounted in bearings at the rear of the lower one, being preferably driven by frictional contact with the lower roller. Or both rollers may be gear driven at the same or varying speeds.

Arranged within a limited distance from and extending the full length of the lower roller is a guide, curved to correspond to the circumference of said roller, and extending preferably from below its axis as far as but just clear of the upper roller. The distance between the guide and the periphery of the lei lower roller must not be more than say a quarter of an inch, and not less than that which will permit the paper, being developed to pass freely between said guide and roller.

When the machine is started the paper to be treated is fed from the table under the lower edge of the guide, which edge may be suitably curved for the purpose, and as the lower roller revolves in its bath containing the developing fluid, the paper is carried upwards around said roller by capillary attraction on a film of developing liquid while passing between the guide until it reaches and passes under the upper roller, which up per roller may if desired act as a squeegee to take off any superfluous developing liquid, or this roller may be wound with a coiled spring, or grooved, to'avoid applying much moisture to the back of the print. Or instead of the guide extending from the point where the paper enters the machine to the point at which it passes between the cleveloper and the pressure roller, or its equivalent, a short guide may be provided at the point of entry, and another guide at the point where the paper passes between the two rollers.

In order that the invention may be clearly understood I have appended the accompanying sheets of drawings.

Fig. l is a diagrammaticalpart sectional view showing the curved guide extending from below the axis of the developing roller P as far as but just clear of the pressure rollerf Fig. 2 is a similar View showing a short guide at the point where the paper enters the machine and anothershort guide at the point where the paper passes between the two rollers.

Fig. 3 shows diagrammatically a modified construction in which the pressure roller is designed to avoid applying much moisture to the back of the print. I

Fig. at is a broken plan view of the modification shown by Fig. 3.

Fig. 5 shows diagrammatically a further modification in which a forked pressure bar is substituted for a pressure roller.

Fig. 6 is a broken plan view of the modification shown by Fig. 5.

A represents the lower roller which revolves in the bath B, D the pressure roller, E the guide, and a the pick-off fingers that remove the print off the roller A as it issues 90 from the machine.

Referring to Fig. 1, when the machine is started the paper 6 to be treated, wh1ch 1s fed from the table T under the lower edge of the guide E, passes between said guide E and the roller A and is carried upwards around said roller A by capillary attraction on a film of developing liquid until 1t reaches and passes under the pressure roller 1), said paper then issuing from the machine as the pick-01f fingers a remove it from the roller A.

In the example illustrated by Fig. 2 instead of the guide E extending from the point where the paper 0 enters'the machine to the pointwhere it passes under the pressure roller D, I have shown a short guide 0 at the point of entry and another short guide 6 adjacent the roller D, the paper 6 as previously described, being carried from the point of entry around the roller A by capillary attraction on a film of developing liquid to the pressure roller D, being then removed from said roller A by the pick-off lingers (L1 as it issues from the machine.

In the method shown by Figs. 3 and 4 the guide E is arranged slightly above the axis of the roller A, and the pressure roller D is wound with a coil of wire (Z thus as the paper is carried from the point of entry around the roller A by capillary attraction on a film of developing fluid to said roller D, it will be seen instead of the paper being pressed, at the point of contact, along the whole surface of the roller D, that Contact between the paper 0 only occurs at the points where the wire (Z touches the back of said paper 0 thus very little moisture is applied to the back of the paper as it passes between the two rollers. Or instead of coiling wire around the roller D, grooves may be formed in the surface of said roller for the same purpose.

At Figs. 5 and 6 I have shown a further modification. In this case instead of the the back of the paper as it passes between the guide E and the roller A, passing under an upper roller, I may employ a bar F provided with curved teeth 7, under which teeth f said paper passes. This bar F may be attached along its upper edge to the guide E, the teeth 7 resting on the roller A, as clearly shown on the drawings.

hat I claim as my invention and desire to secure by Letters Patent is 1. A machine for developing photographic prints comprising a developer roller revolvably mounted in a bath containing a developing fluid, a pressure medium mounted above and in contact with said developer roller, and a guide arranged in juxtaposition and extending from the point where the print is fed into the machine around an arc of the developer roller, between which guide and developer roller the print to be developed is carried upwards on a film of the developing liquid before passing under the pressure medium.

2. In a device of the character described a roller arranged in a bath of developing fluid, means for guiding a photographic print upon the roller and around its are, said print carried on the roller by capillary attraction, pressure means arranged adjacent said guide means and associated with the developer roller for contact with the print, said means having but portions of its surface contacting with the print.

3. In a device of the character described a roller arrangedin a bath of developing fluid, means for guiding a photographic print upon the roller and around its arc, said print carried on the roller by capillary attraction, a pressure roller arranged adjacent said guide means in association with the first mentioned roller and for contact with the print, said roller having helical shaped means upon its surface whereby but the helical means of the roller contacts wit-h the print.

In testimony whereof I affix my signature.

BENJAMIN FAIRFAX HALL.

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